This invention relates generally to photocopying apparatus and particularly to apparatus for removing sheets from the photosensitive surface of a photocopying apparatus.
U.S. application Ser. No. 55,523, filed July 9, 1979, now U.S. Pat. No. 4,278,341, describes apparatus for removing sheet material from the photosensitive surface of a photocopier in which a leading corner edge of the sheet is directed to an output mechanism which catches the corner and pulls the remainder of the sheet through to the exit station. That application describes a pick-off blade which overlays a marginal portion of the drum photosensitive surface when the front edge of the sheet arrives at the drum surface. The side edge of the sheet slides along the blade interposed between it and the drum surface until it is caught by the output mechanism. Then the blade is pivoted away from the drum surface so that successive portions of the sheet can contact the drum surface fully from edge to edge.
This arrangement provides positive and reliable guidance to a sheet conveyed to the transfer station, but a corner of the sheet is thereby prevented from contacting the drum photosensitive surface and receiving a portion of the developed image carried thereon. The effect is heightened by the need for the blade to overlay the drum surface enough to accommodate side-to-side skew type variations in where the side edges of successive sheets arrive at the drum. Furthermore, not only is the portion of the sheet immediately in contact with the blade kept from contacting the drum surface, but a next adjacent "transitional" portion of the paper--the portion rising from contact with the drum surface to contact with the blade--is also kept out of contact with the drum surface. As the blade height off the drum is increased, to avoid contact with the drum photosensitve surface and the toned image carried thereon, the extent of the "transitional" portion is also increased.
It is a principal object of this invention to provide an improved sheet stripping apparatus operating in accordance with the principles described in application Ser. No. 55,523, and which is reliable, low in cost and simple in operation. Other objects are to provide a sheet stripping apparatus that minimizes the likelihood of damage to the drum photosensitive surface and maximizes the portion of the transfer sheet that may receive developed image from the drum surface.